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Chemistry: Catalase Sample Questions

We did the catalse test in class and I have been able to answer some questions but not all.
Questions:
1) Provide an example of reduction reaction performed by cells in which hydrogen is not added to the reduced compound. (I think it deals with hydrogen peroxide--> to water and oxygen)

2) Would a flase positive due to the reaction between the loop and hydrogen peroxide be due to a lack of specificy or sensitivity of the test system?

3) If a weakly catalase-positive organism itinitially gives a false-negative result and is not checked under the miicroscope, would the result be due to a lack of specificity or sensitivity of the test system?

4) Why is it advisable to perform this test on a known catalase-positive organism simultaneously with the organism you are checking?

5) What is the purpose of adding hydrogen peroxide to the uninoculated tube?

Solution Preview

(1) Provide an example of reduction reaction performed by cells in which hydrogen is not added to the reduced compound.

You're correct. 2 H2O2 ----> 2 H2O + O2

(2) Would a false positive due to the reaction between the loop and hydrogen peroxide be due to a lack of specificity or sensitivity of the test system?

Response: Such a false positive reaction would be due to a lack of specificity in the test system. In other words, the test system is sensitive enough, the problem being that "other" things going on in the test system also gives a "positive" result. Therefore, the issue here has to do with a lack of specificity.

(3) If a weakly catalase-positive organism itinitially gives a false-negative result and ...

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